Electron discharge device



July 28, 1931. G. A. lMcNElLl.

ELECTRON DISCHARGE DEVICE Y. Filed March 26, 1926 Patented `uliy 28K, 1.931

UNITED STA-TES GEORGE A. MCNEILL, 0F NEW YORK, N. Y.,

PATENT OFFICE i l y AssIeNoR To BELL TELEPHONE.LABORA-` TORIEs, INCORPORATED, OF NEW YORK, N. Y., A CORPORATION or NEW YORK ELECTRON DISCHARGE DEvrcE Application ylell March 26, 1926. Serial No. 97,652. 'y

This invention relates to electron discharge devices and more particularly to such devices of high power capacity.

In high power water-cooled electron' discharge devices of the external anode type, it is found necessary to surround the {ilament supporting structure with a cylindrical metal protective shield to prevent arcing between the anode and filament struc ture. This protective shield is usually supported from a corrugated collar frictionally attached to the stern of the enclosing vessel of the device. The corrugated collar is subject to excessive heat generated in the device and due to the difference of expansion and contraction of the metal collar with respect to the glass stein with which it is in contact, there is a possibility of the collar becoming loose or injuring the glass stem, and thereby materially decreasing the operating eliiciency of the discharge device.

An ob]ect of this invention is to provide an eicient shield support which will not be affected by temperature changes.-

A further object of the invention is to eliminate the frictional contact between a metal support and an insulating supporting surface.

In accordance with this invention the protective metal shield surrounding the filament supporting structure is supported from an insulating portion, such as a glass stern, of the enclosing vessel, by means of metal angular spacers or ribs having an edge tapered andV sealed into the glass' stem. These spacers or ribs are preferably of a metal having approximately the same coefficient of expansion'as glass and are positioned around the circumference of the glass stem with their free end surfaces engaging the inner surface of the cylindrical shield and are welded thereto to form a rigid supporting structure. This arrangement provides a support which will-not be affected by temperature changes within the device and also maintains the shield in a xed position. Furthermore, the strain on the refractory wall `is eliminated, since there is no frictional contact between thevmetal and glass elements.

The invention is disclosed in the following i tron discharge device is shown consisting of an enclosing vessel havingA a cup-shaped metal anode portion 10,` anda glass portion 11, hermetically sealed together as shown at 12, in accordance with the metal to glass seal disclosed in W. G. yHouskeeper Patent 1,294,466-, issued February 18, 1919, and entitled Combined metal and'glass structure and method of makingsame. A re-enV trant stem 13 closes the open end of the glass wall 11 and is provided with a cylindrical `supporting wall 14y which projects within the enclosing vessel. A pair of glass tubular extensions 15 are sealed tothe inner end of the stem 13- and are re-entrant with respect to the Stern.

A `tubular extension 16, coaxial with respect to the supporting Vwall 14C, extends from the stein 13 and supports a corrugated collar 17 which carries the supportingrods 18 to which is attached a metallic disc' or block 19. This disc is provided with insulating bushings 21, through which extend metallic rods22 to forni connectors for the filament 23. The rods 22 are preferably afiixed to the disc 19 by ineansv 0f oner or two turns of wire 24 being welded to thefrods on either side of the insulating bushings 21. A central supportingrod 25 extends within the anode 10 from the metal disc 19, 'and carries at its free end a pair of wire helices 26 which support insulating inserts` `27 through which extend metallic hooks f 28. The ilament223 is. preferably of Pfl-'shape andis supported at one end by the hooks 28 and at the other end by the wirehelices 29 which bind the filament to the rods 22. AThe end of each connector 22 extending toward the stem is provided with a slot to receive a leading-in `wire 30 which lis rigidly faistened to the connector by means of a nut 31. A heat deflecting shield 20 having the edge turned up is supported on the collar 17 and located adjacent the inner end of the supporting wall 14, to protect the glass seals from the excessive heat generated in the device and the upturned edge of thev shield presents a surface parallel with a surrounding shield to be hereinafter described so that discharges therebetween are less likely to occur.' 30 extends through an aperture inthe heat deiiecting shield 20 and projects through the tubular extensions 15 on the lass stem and is sealed thereto by means o a copper disc seal 32 as disclosed in W. G. Houskeeper Patent 1,293,441, issued February 4, 1919. The leading-in wire 30 is also provided with a flexible connection in the form of a copper braid, to prevent undue strain on the disc seal 32. A tubular glass i-nsulator 34 surrounds the leading-in wire 30 adjacent the shield 20, and is prevented from shifting, by an enlargement 35 on the leadingin wire 30. This insulator prevents contact of the leading-in wire with the heat deflecting shield 20.`

A Ametallic shield 36 composed of alternate cylindrical and tapered sections welded together surrounds the filament supporting structure and forms a barrier between the anode 10 and the filament supporting structure. This shield forms a large smooth surfaceover which the electric field within the device is dissipated and prevents the occurrence of arcing or corona eilects.

A metallic shield 36a similar to the shield 36 but of larger diameter is concentrically arranged with respect to the shield 36, and adjacent to the seal 12 between the anode 10 and the glass port-ion 11. The smalldiameter end of the shield 36a is fastened to the anode by spinning the edgeV thereof into the ridge formed on the anode; This arrangement forms a good mechanical connection between the shield and the anode andforms an eflicient structure for the protection of the glass seal made at the point l2.

In accordance with this invention the shield 36 is supported from the tubular wall 14 by means of metallic spacing members or ri s 37, of angular cross-section and having one edge 38 tapered to a sharp point. The angular ribs 37 may be of copper, iron, nickel or platinum alloy to provide a supporting rib of metal to which'the shield 36 may be rigidly fastened. While the above metals may be used to advantage to obtain an eflicient support, it is preferable to use a nickel-iron alloy, commercially known as meteor metal, which has. approximately the same co-eicient of expansion and contraction as glass and is relatively inexpensive when compared with platinum or a The leading-in wire y platinum alloy having the same characteristics. The tapered edge 38 of the angular rib 37 is sealed into the longitudinal outer surface of the wall 14, in accordance with the method disclosed in W. G. Houskeeper lPatent l/93,441, issued February 4, 1919. This arrangement is clearly shown in the enlarged detail of Fig. 2. The intimate contact of the glassaroundthe lnifeedge 38provides a secure joint between the'metal and glass and since the amount of-m`etal embedded in the glass wall is relatively small, the expansion of the metal is immaterial. The use of a metal, such as meteor metal, having the same coetlicient as glass further reduces the difference of expansion and contraction. A plurality ofthe spacers or ribs 37 are arranged aroundtheoutercirclnnference of the wall 14 as shown -in F ig. 3 -to form a tripodal support for shield-36- Tt will be seen from Fig. 3 that thefthree angular ends of the ribs 37v engage fthe-inner surface of the shield 36 and maybe securely fastened thereto by any rsuitable means, such as spot welding. This arrangement forms a rigid support for the protective shield V36 and overcomes the difference of expansion between Vthe vmetal partsl and the glass wall 14. 'l l f Attached to the end of the shield 36 and projecting within the anode 10, is a metal cellar 39 which supports metallic rodsf40'. These rods formsupporting members around rwhich the helical wire grid is Wound.. Attached to the free end Aofv the rods 40, is a metallic disc 42,'which vforms a shield between the end of the Yanodevl() and the insulating inserts 27, of the -filament supporting structure. Attached tothe end of the shield 36 adjacent-to the stem i;

13, is a threaded socket 43 whichY islsubstantially in alignment with a tubular extension 44, sealed to the juncture bet-Ween the glass wall 11 and the stem: 13. A-1ne tallic rod 45 extends through the extension 44 and is threaded to the socket 43, the outer end of the rod 45 being sealed to the tubular member 44 by means of a disc seal 46. This arrangement forms Vthe leading-in wire for .the grid 41.A v Y That is claimed is: f c f 1. In an electron discharge device, an enclosing vessel having a'stem of'insula'ting material, a metallic L-shaped angular member having a longitudinal edge embedded in i said stem, and a tubular member surrounding said stem-and metallicV member, said metallic member spacing and supporting said tubular member from said stem.

2.111; an electron discharge device, an :l

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stem and a surface in contact with said tubular member.

3. In an electron discharge device, an enclosing vessel having a stem, a tubular member surrounding said stem, and an angular supporting member of sheet-like material having a surface parallel with said stem engaging said tubular member and having a portion extending lengthwise of said stem and embedded therein.

4. In an electron discharge device, an enclosing vessel having a stem, a tubular member surrounding said stem, and a supporting member of flat material having a tapered edge extending lengthwise of and sealed into said stem, said member having a surface parallel with said stem engaging the inner surface of said tubular member.

5. In an electron discharge device, an enclosing vessel having a stem of insulating material, a tubular metal member surrounding said stem, and an angular supporting rib adjacent to, and extending longitudinally of and embedded'in said stem and supporting said tubular member, said supporting rib being composed of a nickel-iron alloy having approximately the same co-efiicient of expansion as glass.

6. An electron discharge device, comprising an enclosing vessel having a glass portion and a metal portion, said metal portion acting as the anode of said device, an inwardly projecting stem on said glass portion, a tubular wall extending from said stern, a plurality of metallic angular ribs sealed into the outer surface of said tubular wall, a supporting structure on said stem and extending within said anode, a filament supported thereon, a tubular metallic shield surrounding said supporting structure, said shield being supported by said angular ribs, and a wire grid surrounding said filament and coaxial with said anode, said grid being supported on said shield.

7. An electron discharge device having a stem of insulating material, electrodes therein, a tubular member for holding one of said electrodes, and a support for said member comprising a plurality of metallic members spaced around said stem, each of said members having one end embedded in said stem and the other end bent over to form a curved surface to which said tubular member is Welded.

8. In an electron discharge device comprising an enclosing vessel having a stem, a cylindrical wall extending from said stem, a tubular metallic member surrounding said wall, and means for supporting said member from said wall comprising a metallic angle bracket having approximately the same coeilicieut of expansion as said wall, one leg of said bracket being affixed to said member and disposed parallel to said-stem and the other leg of said bracket having an edge extending lengthwise of said stem and embedded therein.

In witness whereof, I hereunto subscribe my name this 24 day of March, A. D. 1926.

GEORGE A. MCNEILL. 

